The present invention relates to a new and improved method of regulating a resuperheated steam turbine, wherein there is carried out a reference value-actual value comparison of the rotational speed and there is derived from the reference value-actual value difference an adjustment or control magnitude which is infed to a regulation valve arrangement. The invention further pertains to a new and improved construction of apparatus for the performance of the aforementioned method aspects.
Steam turbine regulation generally encompasses a rotational speed regulation in the form of a direct rotational speed regulation with an essentially simple closed regulation circuit or in the form of a rotational speed regulation or frequency-output regulation, for instance, by means of an output regulation circuit having a cascade rotational speed regulation circuit. In both instances there is carried out a comparison of the actual value and reference value of the rotational speed and there is directly or indirectly derived from the difference of the reference value and actual value an adjustment or control magnitude.
As far as the stability and quality of the regulation is concerned, i.e., for a rapid and oscillation-free transition between different, steady state rotational speeds following the occurrence of surge-like disturbances, for instance due to load surges at the power supply network of an electrical generator coupled with the turbine, there is required an optimization of the transition behavior of the regulation or control circuit with appropriate damping. For this optimization there are available for complex regulation or control circuits different transmission elements having adjustable or selectable parameters. This is, however, associated with comparatively high circuit expenditure. In particular in the case of installations using mechanical or hydraulic, proportional-functioning rotational speed regulation or control difficulties can arise in attempting to obtain a rapid and oscillation-free rotational speed-transition or change-over behavior. This is especially so in the case of turbine-generator units which work both in the so-called island mode of operation as well as in compound operation.